The present invention relates generally to light detection and packaging and, more particularly, to a device for sensing incident light during photodynamic therapy.
Photodynamic therapy (PDT) is an investigational therapy for myriad human cancers. PDT has been applied as a primary tumor treatment, as an adjunct to surgical tumor resection (i.e., intraoperative PDT), and has been extended as a large area treatment. Generally, PDT involves first treating the tissue with a photosensitizer, followed by illuminating the tissue, typically using a laser source. Evidently, in order to carefully investigate and use PDT, in-situ monitoring of the incident light intensity is required so that the intensity and total dose may be controlled. Not only is it important to measure the incident light intensity, but also it should be measured in real-time during PDT because variations in the laser output or changes in the transparency of the intravesical or intralipid fluid (e.g., due to bleeding) result in fluctuations in the light reaching the tissue surface. The light intensity impinging on surrounding regions due to scattering or reflection should also be measured to avoid potentially detrimental effects.
Presently, in-situ dosimetry devices have been developed which use an integrating sphere at the end of an optical fiber. This device is well-suited for bladder cases in which it is positioned via a catheter. However, since the integrating sphere has a large acceptance angle, it is sensitive to reflected light which renders accurate dosimetry more difficult. Also, the integrating sphere dosimetry device is not easily adaptable for use in other cancers. In applying PDT to other cancers, calculations based on laser power, target surface area, target shape, and reflectivity have been used to estimate the light intensity. Such calculations may be highly inaccurate due to factors such as non-ideal geometry, dynamic changes in the transmission and reflectivity of the intralipid and tissue, respectively, as well as changes in the laser output power. Thus, in order to better understand and control PDT, there is a clear need for further developments in sensors for use with PDT.
Accordingly, an object of the present invention is to provide a light sensor for use with PDT.
Another object of the present invention is to provide a light sensor structure which is safe for use on human patients, and particularly, a light sensor which prevents electrical hazards.
A related object of the present invention is that the light sensor measure light incident on the underlying tissue or surface while being insensitive to light reflected from the tissue.
A further object of the present invention is to provide a light sensor which does not prevent the underlying tissue or surface from being radiated by the incident light.
Another object of the present invention is that the light sensor includes a simple, effective means for attaching the sensor to the nearby tissue.
Yet a further object of the present invention is to provide a light sensor which is well-suited for attaching a plurality of these light sensors in the region undergoing PDT.
Yet another object of the present invention is to provide a sensor which separately and simultaneously measures the incident and reflected light.
The foregoing specific objects and advantages of the invention are illustrative of those which can be achieved by the present invention and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, these and other objects and advantages of the invention will be apparent from the description herein or can be learned from practicing the invention, both as embodied herein or as modified in view of any variations which may be apparent to those skilled in the art.